A printer capable of printing desired information such as texts and images on a sheet-type printing medium, e.g., paper, film, and the like, is widely utilized as a data output apparatus in a word processor, a personal computer, a facsimile, and so forth.
Although various printing methods are available for such printer, recently an inkjet printing method has particularly attracted the attention because of its capability to perform non-contact printing on a printing medium such as paper, ease of color printing, and low noise. In general, a serial printing method is widely adopted because of its low cost and ease of downsizing. According to the serial printing method, a printhead for discharging ink in accordance with desired printing data is mounted, and the printhead is reciprocally scanned in the direction orthogonal to the printing medium conveyance direction.
In such printing apparatus, a printing medium is conveyed by conveyance rollers to pass through the interior portion of the printing apparatus. To stably convey the printing medium, it is a general configuration to arrange the conveyance rollers at two locations: the upstream side (paper-feeding side) and downstream side (paper discharging side) of the printing medium conveyance path.
In this configuration, the conveyance rollers serve to stabilize the printing medium in the printing area. The distance between the ink discharge surface of the printhead and the printing surface of the printing medium largely affects ink landing precision, consequently affecting the quality of the image being printed.
For this reason, the two conveyance rollers are arranged to stabilize (hold) the printing medium in a printing area and to stabilize the distance between the ink discharge surface and the printing surface.
However, at the front end or rear end of the printing medium, the printing medium is conveyed by only one of the conveyance rollers. Since printing medium conveyance is largely affected by the shape of the conveyance path, stiffness (flexibility) of the printing medium and the like, the distance between the ink discharge surface and the printing surface becomes unstable, causing deterioration in printing quality.
Conventionally, there were not many demands for printing at the front end or rear end of a printing medium. Therefore, the distance between the ink discharge surface and printing surface has not raised many problems. However, recently there are many printing apparatuses which can print photograph data, recorded by a digital camera or the like, on the entire surface of a printing medium (so-called rimless printing). Along with this trend, there are increasing, demands for preventing deterioration of printing quality at the time of printing an area (front end and rear end of a printing medium) where the distance between the ink discharge surface and the printing surface is unstable.